Add tests for converting expressions of function types to suspending functional types

compiler/testData/codegen/box/suspendConversion/suspendConversionWithFunInterfaces.kt

@@ -0,0 +1,24 @@
+// FIR_IDENTICAL
+// !LANGUAGE: +SuspendConversion
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun interface SuspendRunnable {
+    suspend fun invoke()
+}
+
+fun foo1(s: SuspendRunnable) {}
+fun bar1() {}
+
+fun bar2(s: String = ""): Int = 0
+
+fun bar3() {}
+suspend fun bar3(s: String = ""): Int = 0
+
+fun box(): String {
+    foo1(::bar1)
+    foo1(::bar2)
+
+    foo1(::bar3) // Should be ambiguity
+
+    return "OK"
+}